全文获取类型
收费全文 | 1269篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 42篇 |
综合类 | 2篇 |
化学工业 | 257篇 |
金属工艺 | 23篇 |
机械仪表 | 35篇 |
建筑科学 | 20篇 |
能源动力 | 41篇 |
轻工业 | 135篇 |
水利工程 | 2篇 |
石油天然气 | 20篇 |
无线电 | 94篇 |
一般工业技术 | 161篇 |
冶金工业 | 353篇 |
原子能技术 | 47篇 |
自动化技术 | 61篇 |
出版年
2023年 | 14篇 |
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 11篇 |
2014年 | 23篇 |
2013年 | 56篇 |
2012年 | 36篇 |
2011年 | 54篇 |
2010年 | 38篇 |
2009年 | 47篇 |
2008年 | 52篇 |
2007年 | 34篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 39篇 |
2003年 | 46篇 |
2002年 | 36篇 |
2001年 | 23篇 |
2000年 | 22篇 |
1999年 | 29篇 |
1998年 | 121篇 |
1997年 | 72篇 |
1996年 | 50篇 |
1995年 | 34篇 |
1994年 | 30篇 |
1993年 | 31篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 15篇 |
1978年 | 5篇 |
1977年 | 13篇 |
1976年 | 17篇 |
1974年 | 4篇 |
1972年 | 6篇 |
排序方式: 共有1293条查询结果,搜索用时 15 毫秒
21.
Kazuyori Urabe Hiromi Nakano Hiroyasu Morita 《Journal of the American Ceramic Society》2002,85(2):423-429
Structural modulations in solid solutions of C3 S doped with various amounts of ZnO were investigated via the selected-area electron diffraction method. Three monoclinic modifications (M(I), M(II), and M(III)) were identified in the solid solutions. The modifications had pseudohexagonal subcells that were modulated to form supercells. Coordinates of the reflections attributable to the supercells could be expressed by the following linear combinations of vectors of the reciprocal lattices: m1 (−2 a */5.4 + 2 b */5.4 − 7 c */5.4) for M(I), m2 (− a */5 + b */5 − c *) for M(II), and m3 (− a */6 + b */6 + 7 c */6) for M(III), m1 and m2 =±1 and ±2, and m3 =±1, ±2, and ± 3. All the monoclinic modifications possessed structural modulations of a one-dimensional type. The modulation waves could be detected as wavy contrasts by high-resolution transmission electron microscopy. 相似文献
22.
The diffusion and adsorption of C.I. Direct Yellow 12 and Blue 15 in water-swollen ordinary cellophane sheets were examined at various ionic strengths. The concentration dependence of apparent diffusion coefficients, Dc, for these dyes was obtained from the diffusion profiles in the substrate, which were measured by the use of the cylindrical film roll method. The decrease of apparent porosity with an increase in the amounts of adsorption was observed. To explain the diffusion/adsorption behaviors of these systems, a variable porosity model was proposed and was applied to analyze the concentration dependence of Dc's. The diffusion/adsorption behaviors of these dyes could be quantitatively described by this model at relatively low ionic strengths. At higher ionic strengths and/or lower values of C, i.e., at the large values of Cim/Cm, where the C's are the concentrations of immobilized (suffix im) and mobile (suffix m) species, it needed to introduce the concept of dynamic equilibria which occurred simultaneously with diffusion but deviated from the true equiliblia measured by the adsorption experiments. 相似文献
23.
Prediction of the biologically active sites in eclosion hormone from the silkworm, Bombyx mori 总被引:1,自引:0,他引:1
Kikuchi T; Okamoto M; Geiser M; Schmitz A; Gohda K; Takai M; Morita T; Horii K; Fujita N 《Protein engineering, design & selection : PEDS》1997,10(3):217-222
The structure-activity relationship of eclosion hormone from the silkworm,
Bombyx mori, was analyzed. First, the probable active residues in silkworm
eclosion hormone and also tobacco hornworm eclosion hormone were predicted
by the average distance map method. To examine the contributions of those
residues to the activity of silkworm eclosion hormone, Gly-substituted
mutants for those predicted residues were produced by site-directed
mutagenesis and their activities were evaluated by a bioassay. Finally,
Glu12, Met24 and Phe25 were estimated to be the crucial residues for the
eclosion hormone activity. The possibility of the development of a blocker
of an eclosion hormone receptor on the basis of the present work is also
discussed.
相似文献
24.
The diffusion of a reactive disperse dye with a vinylsulfonyl group accompanied by simultaneous reaction with the amino end groups in nylon 6 was examined by the method of cylindrical film roll at 70°C and pH 2.2–8.0. The experimental diffusion profiles of the active and fixed species of the dye in nylon 6 were confirmed to be described by the diffusion equation accompanied by the chemical reaction with substrate taking the limited amount of the end groups into account, where the active species of dye were assumed to react only with the free base of amino end groups. The completion of the reaction with the amino end groups was observed in the first layer from the surface at pH 6.0–8.0. The value of diffusion coefficient was constant (8.0 × 10?10 cm2/s) at all the pH's. The product of the second-order rate constant, k2, of reaction of the dye and the dissociation constant, Ka, of the amino end groups was constant (k2Ka = 4.0 × 10?9 s?1) at pH 2.2–8.0. The k2 values of the reaction with various substrates for vinylsulfonyl and monochlorotriazinyl-reactive dyes were compared and the practical dyeing conditions were discussed. 相似文献
25.
A new electrolytic solution based on a mixed solvent of ethylene carbonate (EC) with sulfolane (SL) or -butyrolactone (-BL) has been examined as an electric double layer capacitor. Fundamental properties, such as electrolytic conductivity, viscosity, and thermal stability, were measured for solutions containing quaternary alkylammonium salts as the supporting electrolyte. Maximum conductivities were obtained for the solutions with mixed solvent of 20–40 mol % EC in the EC+-BL system: 1.2–1.3×10–2S cm–1 for EC+-BL dissolving 0.5 M Et4 NBF4 (Et=C2H5). The electrochemical and the thermal stabilities of the solution were dependent on the electrolytic salt as well as the solvent composition. A stable discharge capacitance and a high coulombic efficiency were obtained in a model capacitor using carbon fibre electrodes and the organic electrolyte of EC+-BL/Et4NBF4 (or EC+-BL/Et4NPF6). 相似文献
26.
Poly(L ‐lactic acid) (PLLA: Mw = 19.4 × 104)/poly(ethylene glycol) (PEG: Mw = 400) blend films were formed by use of a solvent‐cast technique. The properties and structures of these blend films were investigated. The Young's modulus of the PLLA decreased from 1220 to 417 MPa with the addition of PEG 5 wt %, but the elongation at break increased from 19 to 126%. The melting point of PLLA linearly decreased with increases in the PEG content (i.e., pure PLLA: 172.5°C, PLLA/PEG = 60/40 wt %: 159.6°C). The PEG 20 wt % blend film had a porous structure. The pore diameter was 3–5 μm. The alkali hydrolysis rate of this blend film was accelerated due to its porous structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 965–970, 2004 相似文献
27.
Lingyun Lyu Takeshi Hanada Naohiro Yamahira Jun Morita Ryota Yamamoto Ken Itomi Takumi Adachi Sho Kubouchi Shin Horiuchi 《应用聚合物科学杂志》2021,138(45):51443
The distribution of nano-sized silica in binary rubber blends is characterized by scanning transmission electron microscopy (STEM) tomography combined with energy dispersive X-ray spectrometry (EDX). 3D distribution of silica is visualized by STEM-EDX tomography with the tilt-series of silicon elemental maps, while the phase-separated morphologies of polyisoprene rubber (IR) and styrene-butadiene rubber (SBR) are visualized by STEM-tomography in high-angle-annular-dark field (HAADF) mode. The combination of STEM-EDX and STEM-HAADF tomography enables us to determine the distribution of silica between the two rubber phases quantitatively even with high contents of silica up to 70 phr (weight parts per hundred rubber). It is found that silica is preferentially distributed in the SBR phase, but it is also distributed in the IR phase when the IR fraction in the total rubber components is higher than 40 wt%. The preferential distribution of silica in the SBR phase improves the dispersion of the IR domains. This is the first use of this technique for a multicomponent polymer system, showing the advantage to characterize the complicated multicomponent polymer composite morphologies. 相似文献
28.
For the effective control of Al introduction to solidified Si during the solidification refining of Si with the Si–Al-based melt for the solar cell material or the LPE Si film growth processes from the Si–Cu–Al solvent, thermodynamic properties of the Si–Al–Cu melt were investigated at 1273 and 1373 K. Activities of Al and Cu in the Si–Al–Cu melt were measured by the equilibration with molten Pb. Also, the excess Gibbs energy of the melt was studied by the ternary regular solution model.
The evaluated thermodynamic properties of the Si–Al–Cu melt indicated that Cu addition to the Si–Al melt brings the smaller activity coefficient of Al and is effective for reducing the Al content of solidified Si from the melt more effectively than its dilution effect for Al. 相似文献
29.
Time Averaging Algorithms with Stopping Rules for Multi‐Agent Consensus with Noisy Measurements
下载免费PDF全文
![点击此处可从《Asian journal of control》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A time averaging technique is introduced to consensus algorithms in networked multi‐agent systems under a noisy environment. Each agent communicates with its neighboring agents via a constant gain, while the time averaging states of the agents are considered as the values for agreement. The variation of the time averaging states then is evaluated at a specific number of iterations, where the number is given explicitly in terms of parameters related to the consensus accuracy and its probabilistic guarantee. This result establishes a rigorous stopping rule for the multi‐agent consensus with noisy measurements. Several results on this type of stopping rules are provided for undirected, directed, and time‐varying communication graphs. These theoretical results are illustrated through numerical examples. 相似文献
30.
Reversible computing is a paradigm where computing models are defined so that they reflect physical reversibility, one of the fundamental microscopic physical property of Nature. In this survey/tutorial paper, we discuss how computation can be carried out in a reversible system, how a universal reversible computer can be constructed by reversible logic elements, and how such logic elements are related to reversible physical phenomena. We shall see that, in reversible systems, computation can often be carried out in a very different manner from conventional (i.e., irreversible) computing systems, and even very simple reversible systems or logic elements have computation- or logical-universality. We discuss these problems based on reversible logic elements/circuits, reversible Turing machines, reversible cellular automata, and some other related models of reversible computing. 相似文献